Many industrial processes need to be carried out under vacuum and it is customary, in such situations, to carry out the process concerned in a chamber that is connected to a vacuum pump. Good design practice indicates connecting the inlet of a vacuum pump directly to the outlet orifice of a chamber being pumped, but this is not always possible or practical due to external design requirements, such as the need to fit the vacuum pumping system in around other components. Thus, conduits and manifolds are often used to provide fluid communication between the various components of a vacuum system. In order to efficiently obtain and sustain a vacuum, it is an accepted principle of vacuum system design (cf. “Modern Vacuum Practice”, 3rd Edition, Nigel Harris, ISBN 0-9551501-1-6, chapter 13), that conduits should be as short and wide as possible. By following this rule, the conductance of the conduit can be maximised, thus reducing its resistive effect on the vacuum system.
In many vacuum systems, an isolator valve is interposed between the chamber being evacuated and the pumping system to enable the two to be isolated, for example, during loading of the chamber or during maintenance of the pumping system. As such, it is possible, and indeed quite commonplace, for an isolator valve to be used to temporarily, or semi-permanently, maintain the chamber and pumping system at different pressures. However, where a pressure differential exists and the isolator valve is subsequently opened, inevitably there will be a rush of gas from the chamber to the vacuum system or vice-versa, depending on the direction of the pressure gradient.
It is common knowledge that sudden rushes of gasses in vacuum systems are undesirable because they can overload, or cause damage to, the vacuum system's components. A further consideration is that a sudden rush of gas can exceed the pumping capacity of the vacuum system, which may not be able to cope with the increased throughput, that is to say, the quantity of gas passing through a cross-section in a given interval of time.
In situations where a vacuum system is suddenly overloaded, there is a risk of mechanical damage being sustained, for example, bearing damage, gear slippage or rotor and/or stator collisions. Sudden overloads can also lead to electrical damage, for example, over-currents or power surges.
In order to combat the above effects, it is well-established practice to include an in-line pressure regulating system to dampen or block sudden changes in throughput. One example of a known pressure regulating system comprises a mechanical regulator valve arrangement that is configured to limit the throughput of gas in a vacuum system above certain pressure differentials, but to allow relatively unimpeded flow of gas below the said pressure differentials. One of the drawbacks of known in-line pressure regulating systems is that they are complex devices that operate on mechanical principles and can thus be costly to install, maintain and repair.
A need therefore exists for an improved and/or alternative type of pressure regulating system, and in particular, one that can be suitably employed to safeguard against damage to vacuum pumping systems during opening of isolator valves.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background.